Little is known concerning the structure, function and biosynthesis of a fungal lipo-peptido-polysaccharide which contains galactofuranosyl residues. Based on the density of the membrane fraction to which it is attached, the resistance of a structurally related exocellular glycopeptide to degradation by proteases and glycohydrolases, and the fact that it is released only if the membrane to which it is attached is completely solubilized, we have proposed that lipo-peptido-polysaccharide is a structural component of the fungal vacuole (lysosome) and that it serves as a barrier between the lytic enzymes within the organelle and the membrane of the vacuole. The proposed work for this granting period centers around 1) further characterization of the lipo-peptido-polysaccharide using C13-and P13- nuclear magnetic resonance spectrocopy, and chemical techniques previously described (1974) J. Biol. Chem. 249, 2063, 2072, 2) determination of the amino acid sequence of the polypeptide(s) to which the saccharides of the exocellular peptidophosphogalactomannan are attached, 3) determination of the specificity of two partially purified mannosyltransferases using various potential acceptors derived from peptidophosphogalactomannan and lipo-peptido-polysaccharide, and 4) isolation of quantities of P. charlesii protoplasts, followed by osmotic lysis of the protoplasts and separation of the membranes by density gradient centrifugation. The membranes will be examined to determine which contain galactofuranosyl residues, a procedure which is used as a marker of lipo-peptido-polysaccharide.